<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <script>
        window.onload = () => {
            let btn = document.getElementById("btn");
            let sheng = document.getElementById("sheng");
            let shi = document.getElementById("shi");
            let xian = document.getElementById("xian");
            btn.onclick = () => {

                let index_sheng = sheng.selectedIndex;
                let value_sheng = sheng.options[index_sheng].innerHTML;

                let index_shi = shi.selectedIndex;
                let value_shi = shi.options[index_shi].innerHTML;

                let index_xian = xian.selectedIndex;
                let value_xian = xian.options[index_xian].innerHTML;


                document.getElementById("div").innerHTML = `${value_sheng}省${value_shi}

                ${value_xian}
                `


                console.log(sheng.name)

            }






        }
    </script>
</head>
<body>


<form action="">
    <select id="sheng">
        <option value="">请选择省</option>
        <option value="河南">河南</option>
        <option value="广东">广东</option>
    </select>
    <select id="shi">
        <option value="">请选择市</option>
        <option value="郑州市">郑州市</option>
        <option value="广州">广州</option>
    </select>
    <select id="xian">
        <option value="">请选择县</option>
        <option value="叼毛">叼毛</option>
        <option value="天河区">天河区</option>
    </select>
    <input type="button" value="点击" id="btn">


    <div id="div"></div>
</form>
</body>
</html>